LEPTIN FACILITATES AND INHIBITS SEXUAL-BEHAVIOR IN FEMALE HAMSTERS

Food deprivation decreases fertility in female mammals in part by inhi biting sexual behaviors. Genetically obese ob/ob mice, like food-depri ved wild-type animals, are also infertile; treatment of ob/ob mice wit h leptin, the adipocyte-derived protein that they lack, corrects some of their reproductive deficiencies. We tested the hypothesis that lept in treatment would prevent the suppression of sexual receptivity that is caused by food deprivation in female Syrian hamsters. Instead, we f ound that treatment with murine leptin facilitated female sexual behav ior in ad libitum-fed hamsters, but not in food-deprived animals. In f ood-deprived hamsters, leptin treatment actually intensified the inhib ition of lordosis. Food deprivation decreased detectable estrogen rece ptor immunoreactivity (ERIR) in the ventromedial hypothalamus (VMH), b ut the leptin-induced changes in female sexual behavior were not accom panied by parallel changes in VMH ERIR. Thus leptin facilitates estrou s behavior in hamsters, but it does not overcome the lordosis-inhibiti ng metabolic cues produced by acute food deprivation. Because circulat ing leptin levels are directly related to body fat content, an implica tion of these findings is that elevated levels of adipose tissue could have a positive influence on sexual responsiveness.